Direct current electromagnet is extensively used as electromagnet controlling element. PTC element is a ceramic thermistor with positivetemperaturecoefficient.
直流电磁铁是广泛应用的电磁控制元件，PT C元件是具有正温度系数特性的半导体陶瓷热敏电阻。
2
Positivetemperaturecoefficient (PTC) thermistor and triple frequency harmonic filter can reduce zero sequence voltage when a nonlinear resistance is used to prevent ferroresonance.